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Host-Side Single Cell Lithium Battery Gauge

RT9428

For the embedded Fuel Gauge function, the state-of-charge (SOC) calculation is based on the battery voltage information and the dynamic difference between battery voltage and relaxed OCV, by using iteration to estimate the increasing or decreasing SOC.

Voltage-based algorithm can support smoothly SOC and does not accumulate error with time and current. That is an advantage compared to coulomb counter which suffer from SOC drift caused by current-sense error and battery self-discharge. The disadvantage of voltage-based fuel gauge, it can report incremental SOC (%), but can't report capacity (mAh).

A quick sensing operation provides a good initial estimate of the battery's SOC. This feature allows the IC to be located on system side, reducing cost and supply chain constraints on the battery. Measurement and estimated capacity data sets are accessed through an I2C interface.